A typical prior art hole cutter includes a cylindrical blade body defining a plurality of saw teeth on the cutting edge of the blade body, and one or more apertures formed through an intermediate portion of the blade body. Typically, smaller diameter hole cutters have fewer apertures formed through the blade bodies, and larger diameter hole cutters have more apertures formed through the blade bodies. The apertures formed through prior art hole cutter blade bodies may define a variety of different configurations to facilitate inserting a tool into the apertures, such as a screw driver, to remove circular work piece slugs from the interiors of the blade bodies.
One of the drawbacks encountered with prior art hole cutters is that chips or dust, particularly when cutting wood, collects within the interiors of the hole cutters between the work piece slugs and the caps on the non-working ends of the hole cutters. The apertures formed in the side walls of the blade bodies are designed to allow the insertion of screw drivers or like tools to remove work piece slugs, but are not configured to allow the chips or dust generated during cutting to flow through the apertures and away from the interiors of the blade bodies. The chips and dust that collect within the interiors of the blade bodies can become compacted and rapidly fill the hole cutters. Chips and dust also collect at the interfaces between the blade bodies and work pieces, such as between the external surfaces of the blade bodies and the work pieces. The chips and dust that collect at the interfaces of the blades bodies and work pieces can become heated due to frictional forces created between the rotating blade bodies, collected chips and dust, and work pieces. The thermal energy created by such frictional forces can be sufficient to cause the paints or coatings on the external surfaces of the blade bodies to become soft or gooey. The collection of chips and dust within the interiors of the blade bodies and/or at the interfaces of the blade bodies and work pieces can significantly reduce the cutting efficiency and overall cutting speed and/or blade life of such hole cutters.
Another drawback encountered with prior art hole cutters is that the blade bodies are relatively thick, typically on the order of at least about 0.05 inch thick. It has heretofore been believed that such wall thicknesses were required in order to provide the hole cutters with sufficient rigidity and strength to withstand the forces encountered during cutting. For example, the United States General Services Administration standard (A-A-51135, October 1984) has taught that hole saws measuring 1⅜ inches in diameter and larger should define a blade body thickness of at least about 0.047 inch. The widths of the cutting teeth are typically about the same as the thicknesses of the blade bodies. As a result, the cutting teeth are relatively wide, thus generating a substantial volume of chips and/or dust during cutting. The rate at which the chips and/or dust are generated during cutting can rapidly overcome any ability of such prior art hole cutters to allow for the egress of chips or dust away from the interiors of the hole cutters and/or the interfaces between the blade bodies and work pieces. As a result, prior art hole cutters can become rapidly filled with chips and/or dust, and/or can rapidly collect chips and/or dust at the interfaces of the blade bodies and work pieces, giving rise to substantial heat during cutting that can soften or otherwise turn the paints or coatings on the hole cutters soft or gooey. The soft or gooey paints or coatings, combined with the collected chips and dust, further degrade the cutting efficiency of the hole cutters and reduce overall cutting speed and/or blade life.
Accordingly, it is an object of the present invention to overcome one or more of the above-described drawbacks and/or disadvantages of the prior art.